CODEWITHSUNDEEP
iosobjective-cuicollectionview
user6092898
user6092898

Reputation:

Images changes when UICollectionView is scrolled

Im using a UICollectionView to load images.

Following is my code. ImageArray will contain the url for each images that has to be loaded. and In my code, Im trying to give a round border around the entire collectionview

- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
    static NSString *identifier = @"Cell";

    UICollectionViewCell *cell = [collectionView dequeueReusableCellWithReuseIdentifier:identifier forIndexPath:indexPath];

    UIImageView *recipeImageView = (UIImageView *)[cell viewWithTag:100];

    CALayer* layer = cell.layer;

    [layer setCornerRadius:4.0f];
    [layer setBorderColor:[UIColor colorWithWhite:0.8 alpha:1].CGColor];
    [layer setBorderWidth:1.0f];


    if ([ImageArray count] >0){

            dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_BACKGROUND, 0), ^(void) {
                NSData *data0 = [NSData dataWithContentsOfURL: [NSURL URLWithString:[ImageArray objectAtIndex:indexPath.row]]];
                UIImage *image = [UIImage imageWithData: data0];

                dispatch_sync(dispatch_get_main_queue(), ^(void) {
                    recipeImageView.image = image;
                });
            });

    }

    [spinnerShow stopAnimating];

    cell.layer.shouldRasterize = YES;
    cell.layer.rasterizationScale = [UIScreen mainScreen].scale;

    return cell;
}

The problem that im facing is that,

  1. The images contents are changing if im scrolling it horizotally
  2. The round border is being rendered to each cells of collectionview but not the round border is not being rendered to the entire UICollectionView.

How can I sort this out?

Upvotes: 0

Views: 805

Answers (4)

Tiko
Tiko

Reputation: 570

in UICollectionViewCell is a method prepareForReuse which you should override and set UIImageView's image to nil

Upvotes: 1

sasi kumar
sasi kumar

Reputation: 753

UICollectionView will reuse the existing cell. So there might be a possibility that your imageView in collectionViewCell will display the previous loaded image.

Its not a perfect solution, but give a try like passing nil or default image to imageView before starting downloading like

recipeImageView.image = nil;

before

if ([ImageArray count] > 0) {

Upvotes: 1

Dominic
Dominic

Reputation: 258

You are referencing the cell's tag but all cells have the same tag value of 100. This means that you are going to get unpredictable results and this is why your images keep changing.

Upvotes: 0

Ketan Parmar
Ketan Parmar

Reputation: 27428

You can set border and corner radius to collection view like,

  collectionView.layer.borderWidth = 1.0;
  collectionView.layer.backgroundColor = [UIColor colorWithWhite:0.8 alpha:1].CGColor;
  collectionView.layer.cornerRadius = 4.0f;

And don't set it in cellForItemAtIndexPath. Set it in viewdidload, so that it loads once, otherqwise it will set everytime when cell will deque!

Second thing, as suggest in one comment you should use SDWebImage for caching the images.

Make sure you set right constraints if you are using autolayout.

Hope this will help :)

Upvotes: 0

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